Snap switch mechanism



Och 1963 J. o. ROESER 3,105,

SNAP SWITCH MECHANISM Filed Feb. 8, 1960 4 Sheets-Sheet 1 Z2 fj 40 70 65% 5 INVENTOR. v 75 116 JO 1963 .1. o. ROESER 3, 05,885

SNAP SWITCH MECHANISM Filed Feb. 8, 1960 4 Sheets-Sheet 2 W 7. 4 IJAJZ Oct. 1, 1963 J. o. ROESER 3,

SNAP SWITCH MECHANISM Filed Feb. 8, 1960 4 Sheets-Sheet 4 INVENTOR. 360 I 55 75220 afiasefl I 355 wm/a/z/ United States Patent 3,105,885 NAP SWITCH MECHANISM John G. Roeser, Park Ridge, 111., assignor to Illinois Tool Works Inc, a corporation of Delaware Filed Feb. 8, 19%, Ser. No. 7,484 14 Claims. (Cl. 20067) This invention is concerned with an electrical switch, more particularly the type of electrical snap switch having a low travel and actuated by a relatively very small movement of an operating member. This application is a continuation-in-part'of my copending application Serial No. 589,714, filed June 6, 1956, now abandoned.

Low travel switch mechanisms find wide use in industry and in aircraft. In many installations, particularly those in aircraft, the entire mechanism must be sealed. Prior low travel switch mechanisms with which I am familiar have had seals which have been prohibitively expensive, or which have not had satisfactorily long service life or did not offer a true hermetic seal. In addition, the springs used in such switches have not been entirely satisfactory. Such springs often comp-rise leaf springs deformed more or less to C-shape for effecting an overcenter snap action. Such springs have had holes in them for receiving mounting parts, thus weakening the springs, or have had sharp bends therein, or have had to be installed in cooperation with expensive mounting parts. Sharp bends in leaf springs obviously are to be avoided,

since sharp bends cannot be made after tempering of the metal without running a substantial risk of fracture, and tempering of sheet metal springs after such bending is likely to lead to warpage of the springs.

Accordingly, it is an object of this invention to provide an improved low travel switch mechanism.

It is a further object of the invention to provide an improved sealing structure in such a switch mechanism.

In addition, it is an object of this invention to provide an improved leaf spring for operating an overcenter low travel switch mechanism, which spring is readily cooperable with stamped sheet metal parts, and which has no weakening apertures or sharp bends therein.

Another object is to provide a sealed control switch adapted for operation by movement relative to the switch of external structure and having an improved construction which provides for adjustment of the switch to respond to different positions of external structure relative to the switch and which assures precise operation of the switch for every position of adjustment.

Another object of the invention is to provide an enclosed low travel control switch having an improved construction which provides for extremely precise and reliable operation of the switch in response to location of external structure in a critical control position relative to the switch, which position can be infinitely and precisely adjusted to any desired location within a wide range of positions relative to the switch.

Another object is to provide a low travel control switch isolated from the external environment in a housing and operated by new and improved control structure supported on the housing and having an improved construe tion which assures precise and reliable operation of the switch in response to movement of external structure into a critical operating position relative to the switch, while at the same time providing for infinite adjustment of the control structure through a wide range of movement to vary the critical position relative to the switch in which external structure will produce the desired precise operation of the switch.

A further object is to provide an improved control switch, as recited in the preceding objects, which has an improved construction that provides at once for sealing the switch within a housing and for adjustment of the switch through operation of externally accessible adjusting elements to respond with great accuracy and dependability to the location of external structure in different control positions relative to the switch.

It is further an object of this invention to provide a spring for a switch mechanism as in the preceding paragraph wherein the spring has improved spring characteristics.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

FIG. '-1 is a perspective view of the outside of a case of a switch mechanism constructed in accordance with the principles of this invention;

FIG. 2 is a longitudinal sectional View through the switch mechanism as taken along the line 22 in FIG. 1;

FIG. 3 is a view similar to FIG. 2 showing the parts in a different position of operation;

FIG. 4 is a fragmentary view partially in substantially vertical section as taken along the line 44 in FIG. 2;

FIG. 5 is a plan view of the switch blade with which the spring cooperates;

FIG. 6 is a plan view of the novel spring;

FIG. 7 is a side view of the spring as prestressed;

FIG. 8 is a side view of the spring substantially as installed;

FIG. 9 is a side View of la modified form of switch;

FIG. 10 is a top View of the switch actuator of FIG. 9;

FIG. 11 is a top view of the movable switch blade;

FIG. 12 is a plan view of the fixed switch blade;

FIG. 13 is a plan view of the stop for the movable switch blade;

FIG. 14 is a perspective view of the spring;

FIG. 15 is a side view of the outside of a modified switch mechanism;

FIG. 16 is a fragmentary longitudinal sectional View of the modification of FIG. 15 as taken along the line 1616 in FIG. 17;

FIG. 17 is a fragmentary cross sectional view along the line 1717 in FIG. 15;

FIG. 18 is a detail view of a switch actuating part;

FIG. 19 is a longitudinal sectional view showing the switch parts in a different position of operation;

FIG. 20 is a perspective View of an enclosed control switch forming another embodiment of the invention;

FIG. 21 is a longitudinal sectional view on an enlarged scale taken with reference to the line 21-21 of FIG. 20;

FIG. 22 is a horizontal sectional view taken along the line 2222 of FIG. 21;

FIG. 23 is a perspective view of an enclosed control switch forming another embodiment of the invention;

FIG. 24 is a fragmentary vertical sectional view taken with reference to the line 24-24 of FIG. 23; and

FIG. 25 is a fragmentary sectional view taken along the line 25-25 of FIG. 24.

Referring now in greater particularity to the drawings, and first to FIGS. 14, there is shown a box-like housing or case 20 open on one side and having a cover 22 suitably sealed in place thereon. An electrical connector 24 is provided at one end of the housing or case, and is provided with external screw threads, as is well known in the art. A tubulation 26 is provided on the housing for evacuation of air, this tubulation being sealed following evacuation, all as is well known.

An annular ring or boss 28 is sealed to the housing near one end thereof, and is provided with a radially inwardly extending annular flange 30 (FIG. 4). The flange is provided with a seat 32 on the top surface thereofi A Sylphon bellows 34 depends from the flange 30. The

uppermost corrugation of the bellows embraces the flange and is solder sealed thereto along the top of the flange.

The flange 3-6 of a tubular member or bushing 38 seats against the top corrugation of the bellows adjacent the seat 32 and is soldered. or brazed thereto. The tubular body or shank of the member or bushing 38 depends within the bellows, but terminates short of the closed end 41 of the bellows. A cross pin 42 is held by the tubular body of the bushing 38 and a rocker arm or operating member 50 is pivoted intermediate its ends on the cross pin 42, and comprises an operating lever extending through the wall of the housing 20-.

The rocker arm or operating member is provided adjacent its upper end with a tapered portion 52 receiving the collar 54 of an external lever arm 56. The lever arm 56 is made of strap material and comprises a pair of parallel strips having a roller 58 rollingly secured on a pin between the tips thereof. A nut '60 is threaded on the upper end of the rocker arm or operating member and clamps the external lever arm in proper position.

The closed lower end 41 of the bellows is provided with a central aperture seating against a shoulder 62 on the rocker arm or operating member The bellows is sealed to the rocker arm or operating member at this position by means of solder, brazing or some other suitable means. Further to insure a proper seal, to prevent entrance of moisture, dirt, and other foreign matter to the inside of the bellows, there is provided a mass of resilient material 64. This mass of resilient material is positioned between the bushing or member 38 and the rocker arm or operating member 50. However, it is terminated short of the corrugations of the bellows as is indicated at 66. This material preferably is a silicone rubber, or some other suitable material such as sponge rubber granules in a resilient setting vehicle. The ring or boss 28 is solder sealed to the housing and to the bellows, and the bellows is solder sealed to the rocker arm or operating member, the bellows and rocker arm or operating member further being sealed by the silicone rubber or other material 64. A flexible or rocking operating member thus is provided extending interiorly and exteriorly of the housing without allowing the entrance of air orany other substance into the housing.

blade is of generally rectangular outline, including an anchoring end 118 having an aperture 120 therein for receipt of the terminal 100. At the opposite end there is a contact carrying portion 122 carrying the button contacts 124 engageable with the fixed contacts. The contact carrying portion 122 is provided along its inner edge with a rectangular notch or female slot 126. The

anchoring end 118 and con-tact carrying end 122 are with a notch or female slot 132 confronting the notch or female slot 126, but spaced therefrom.

A C-shaped overcenter spring 134 extends between the notches or female slots 126 and 132 and normally holds the contact 124 up against the fixed contact 114. "The shape of the C-shaped spring is of considerable importance, and is shown in outline in FIG. 6. The spring is provided with a central enlarged body portion 136 taper ing toward the opposite ends to form necks 138 of restricted width. Tabs 140 immediately past the necks extend laterally outwardly therefrom. The spring 134 normally is prestressed to a shallow C-shaped configuration as in FIG. '7. The spring then in inserted with the necks or restricted portions138 in the notches or female slots 126 and 132. This causes compression or deformation of the spring to the shape shown in FIG. 8, the spring thereby being under compression.

The actuating button is bifurcated and engages the legs 128 approximately at the position indicated by the A polygonal plate 68 is secured. against a shoulder 76 7 adjacent the opposite end of the rocker arm or operating member 50 by means of a nut 72. This polygonal plate has a pair of lateral shoulders 74 and a central tongue 76 extending therefrom and having an upwardly directed tip 78. A pair of springs 81 lying on opposite sides of the tongue 76 is stretched between suitable anchor holes in the shoulders 74 and a pin 82 extending from the rear wall of the housing or case 20. This normally holds the operating lever or rocker arm 50 and the external lever 52 in the position shown in FIGS. 1 and 2, but allows them to move to the position shown in FIG. 3.

A cam follower or operating arm 84 is pivotally mounted on the pin 8). and is provided with a cam surface 86 engageable with the tongue 76 and upturned tip 78 thereof. The cam member 84 also is provided at its outer end with a horizontal plate 88 engaging a switch operating button 96 as will be explained hereinafter.

The switch mechanism, generally designated by the numeral 92, is mounted within the housing or case 20, as by being suitably pinned or bonded against one surface thereof. The switch mechanism includes a plastic case 94 having a shelf 96 near one end thereof on which a switch blade 98 is secured in known manner by the rivetlike terminal 1%. The case slopes downhill therefrom as at 1412, having a central raised protuberance or hill 1114, to a floor 106. A fixed switch contact 108 is mount ed on the floor by means of a terminal 110. A further shelf 112 is provided, and a second fixed switch contact 114 is mounted thereon by means of a terminal 116.

The configuration of the switch blade 98 will be seen more particularly with regard to FIG. 5. The switch Xs in FIG. 5. Thus, when the button is forced down by the plate 88, it forces the legs 128 down until the switch blade 98 overcenters. the contacts 124 from the fixed contact 114 to the fixed contact 108. 'When the button 90 is released the inherent. resiliency of the blade 98 tends to return it toward the raised position, and this tendency is completed by the force of the spring 134 upon overcentering. It will be apparent that the spacing between certain of the parts, notably the fixed contacts 168 and 114, has been exag gerated for purposes of illustration.

It will be observed that the C-shaped actuating spring in this instance is devoid of weakening apertures and sharp bends. The enlargement of the central body of the spring provides more metal at the point of greatest strain, and also provides an improved spring action.

The principles of the invention are applicable also to a single throw snap switch as is illustrated in FIGS. 9-14.

More specifically, there is provided an insulating base 142 having a fixed contact blade 144- mounted therebeneath by means of plastic rivets 146. The blade is pro vided adjacent its outer end with a fixed contact 148.

On top of the insulating base 142 there is provided a moving switch blade 150, also held by the plastic rivets i 146. The switch blade 15! is provided at its outer end with a notch or female slot 152, and immediately adjacent thereto there is provided. a contact button 154. The switch blade is provided with a mounting base 156, and the fixed switch blade or contact 144 similarly is provided with a body portion 158, both body portions being apertured for receipt of the rivets 146. 'A tall or terminal extends obliquely in one direction from the body portion 156, while a similar tail or terminal 162 extends obliquely or diagonally in the opposite direction from the body 158.

A flexible actuator 164 of rectangular outline is .pro

vided with an anchor or body portion 166 at one end thereof, being apertured for receipt of the rivets 146, and being interposed between the switch blade base 156 and insulating base 142. There is an operating portion 168' at the opposite end, joined to the anchor by means of longitudinally extending legs 170 lying on opposite sides The spring 134 then snaps of the blade 150. There is provided a notch or female slot 172 confronting the notch or female slot 152. The operating portion 168 of the actuating member is de formed slightly upwardly for engagement with a suitable button or other member for moving the actuating member downwardly.

The switch of FIGS. 9-14 is completed by a fixed stop 174 comprising a base 176 and a blade 178. The base is apertured for receipt of the rivets 146, and the blade 178 is bent slightly upwardly. A C-shaped spring 180 similar in configuration to that previously disclosed is mounted between the notches or female slots 152 and 172. The actuating lever 164 normally is bent slightly upwardly, and is held against the fixed stop by the spring 189. When the actuating lever is pushed down, the spring 180 overcenters, and the switch blade 15-0 is snapped up, movement being limited by the fixed stop 174. Release of the operating lever causes it to tend to return to its raised position by virtue of its inherent resilien-cy, and overcentering of the spring 189' snaps the switch blade down and the actuating lever up to the positions shown in FIG. 9. Actuator 364 may have no bias so that the switch will remain in either of its extreme positions.

It will be apparent that the embodiment of the invention as shown in FIGS. 9-14 could be used in a sealed housing such as has been disclosed with regard to FIGS. l-3.

A modification of the invention is shown in FIGS. 15- 19. In this modification, many of the parts are equivalent to, or identical with parts previously shown and described. Accordingly, similar numerals are utilized to identify similar parts, such numerals having the sufiix (I added thereto. Thus, the switch includes the box-like housing or case 20a having a cover sealed thereon, and having an electrical connector 24a at one end thereof. The tubulation 26a again is provided for exhausting air from the housing or case.

There is somewhat of a modification in the sealing of the rocker arm or operating member Siia to the case or housing. ing or case 29a in spaced apart relation, and a yoke 202 is secured to the rocker arm Stla and has a pair of depending arms 264 pivotally secured to the flanges by a pair of pivot pins 286. The Sylphon bellows 34a is sealed to the rocker arm or actuating rod 50:: at 268 where the rocker arm passes through the yoke. The bellows also is sealed to the top of the case or housing 26a at 210.

The external lever arm 56:: comprises a single strip of sheet material rotatably carrying a roller 53a at the outer end thereof. The major portion of the lever arm 56ais aligned with the center arm of the rocker arm 50a, but the lever arm is provided with an offset portion 212 whereby a mounting base 214 of the lever arm fits at one side of the rocker arm. This base 214 of the lever arm is secured to a short cross shaft 216 by means of a splined reduced end 218 on the cross shaft fitting through the base 214, the reduced end being peened over as at 220.

The rocker arm 59a is provided at its upper end with an enlargement or housing 222, and the cross shaft 216 extends through this enlargement. The cross shaft is provided intermediate its ends with a splined portion 224, and a tapered locking bushing 226 is trapped between the splined portion 22-4 and the base 214 of the lever arm 56a. This tapered bushing fits in a complementary tapered bore in the enlargement 222, and the cross shaft 216 on the opposite side of the splined portion 224 fits through a cylindrical bore, whereby the cross shaft is rotatably or pivotahy journaled. A nut 22% and lock washer 23%? are provided on the threaded outer end 232 of the cross shaft for tightly locking the cross shaft in any desired position of adjustment. Preferably, the nut 228 and lock washer 231' are of the preassembled type known as Keps.

A worm 234- extends tlnough the upper portion of the A pair of flanges 2% upstands from the hous- 6 enlargement 222, and the thread 236 thereof engages the splined portion 224 of the cross shaft 216. The screw 234 is provided at one end with a slotted head 23%, and at the other end the screw is peened over at 244} against a retaining washer 242.

Upon loosening of the nut 22% and lock washer 230, the screw 234 can be turned by a screwdriver to adjust the lever arm 56a up and down relative to the rocker arm 5%. For example, in FIG. 15 the lever is shown in solid lines in one possible position of operation, and is shown in dashed lines in another possible position of operation. When the lever arm 56a is adjusted to proper position, the nut 228 is retightened against the lock washer 23% to lock the lever arm in adjusted position.

The actuating member secured to the =lower end of the rocker arm 50a is somewhat difierent, and comprises a rigid backup plate or arm 244 having a prestressed steel spring arm 246 secured against it. The relation of the prestressed spring arm 24-6 and of the backup plate- 244 is shown irr FIG. 18 before assembly, although following assembly the prestressed spring arm 246 is held flat against the backup plate 244 as may be seen in FIG. 16. The spring arm and backup plate are clamped against a shoulder on the rocker arm Sila by the nut 72:: threaded on the reduced lower end of the rocker arm.

The backup plate 244 is provided with laterally extending ears, and tension springs 8% are stretched between these ears and anchor posts 247 secured on the inside of the top of the case. A bumper 248 also is secured on the inside of the case to lirnitthe upper position of the spring 246 and backup member 244. Normally, the spring 246 remains against the backup member 244. However, there are instances wherein the follower roller 53a might move a rather substantial distance, much more than is necessary for actuating the switch, and the spring lade 246 then is capable of bending relatively upwardly away from the backup member to prevent damage to the switch mechanism.

The switch mechanism 92:: is generally similar to that previously described. The switch mechanism differs in that upstanding flanges 250 are provided on top of the switch mechanism, and an operating lever 252 is pivotally connected between these flanges, and abuts the top of the switch operating button 9&1. The operating lever 252 is provided at its free end with an upturned leg 254 having a button 2-56 thereon engaged by the spring 246. An abutment 253 is provided on top of the switch mechanism to limit downward movement of the operating lever 252, and hence to prevent undue movement of the internal parts of the switch mechanism. The normal quiescent position of the spring 246, the backup member 244, and the operating lever 252'is shown in full lines in FIG. 16. Dashed lines in this figure illustrate the manner in which the operating member can be moved against the stop or abutment 258, with the spring 246 thereafter flexing relatrvely upwardly away from the backup member 244.

The switch operating mechanism, similar to that previously described, comprises a plastic case 94a having a relatively low shelf 96a near one end thereof, and on which the switch blade 98a is secured, by means such as a rivet-like terminal Tisha. The case slopes slightly downhill therefrom at 162a, having a central raised protuberance or hill 104a, to a floor 3436a. A fixed switch contact 108a is mounted on the floor by means of a terminal 119a. A further, and relatively higher, shelf 1120 is provided adjacent the opposite end of the case, and a second fixed switch contact 114a is mounted thereon by means of a terminal 116a.

It will be observed that both fixed contacts, including the fixed contact 198a, are higher than the shelf 96a. In accordance therewith, the switch blade 98a, which otherwise is substantially similar to the switch blade 98a pre viously described, is prefiexed upwardly. A rigid sheet metal stamping 260 is secured by the terminal 10012 on top of-the central tongue a, and forms a limit stop overlying the support end of the tongue 130a to limit 7 upward swinging movement of the tongue. As will be observed, the tongue extends beyond the rigid stamping End, and the tip thereof is accordingly flexible, and this helps in overcentering the C-shaped spring 134a, this spring being substantially identical with that previously described.

The internal operation of the switch mechanism is substantially identical with that previously disclosed. The bottom of the button 9th: is generally saddle shaped, and hence engages the side arms of the spring blade 98a, while spanning the tongue 139a and the rigid stamping 26%). It has been found in practice that the prestressed switch blade lasts substantially longer in service than one which is not prefiexed. Damage to internal parts of the switch mechanism by unwonted movement of the external parts is avoided by the prestressed spring blade 245. The adjustable mounting of the external lever arm 56a allows a single basic switch to be adapted to a great variety of applications without modification.

The shape of the -C-shaped spring and its cooperation with other parts in each example is believed to be unique. The C-shaped spring is stronger and easier to fabricate, and has longer life than any prior art springs with which I am familiar. tion due to the enlarged central portion and tapering end portions. The particular bellows arrangements shown and described afford a substantially leakproof seal for the housing or case, they are inexpensive to produce, and they are possessed of long life.

In each case, the spring bears against a part relatively near an anchor, as the parts having the recesses 132 and 152, which therefore is aptly termed a reaction member, and against a more remote part in the nature of a blade having a reaction portion, as the parts having the recesses 126 and 172.

It will be observed that the C-shaped spring is symmetrical. Accordingly, it can be inserted in either of two possible positions. This materially simplifies and speeds assembly.

Having reference to FIGS. 20 to 22, the switch 298 forming the modified embodiment of the invention shown in these figures comprises a precision switch unit 380, FIG. 21, rigidly supported within a sealed housing or case 392 for operation by movement of external structure 304 (illustrated in phantom in FIG. 4) into a critical control position relative to the switch.

In moving into its critical switch operating or control position, the external structure 304 engages and acts against a roller 306 carried by the projecting end of a swingable control arm 368. The control arm 303 is connected to operate the switch unit 300 through precision control structure which maintains the sealed integrity of the switch housing 302, while at the same time providing, as will presently appear, for infinite adjustment of the control arm to effect a corresponding infinite adjustment relative to the switch'of the critical position into which the external structure 304 must move in order to eifect operation of the switch unit 300.

Thus, swinging movement of the arm 308 in response to engagement of the roller 306 by an external part 304 (which may be a movable machine element, for example) is transmitted through the housing 302 by means of a rotary control shaft 310.

As shown in FIG. 21, the lower end of the shaft 310 is turned down to form a smooth cylindrical shaft section 311 which is journalled in a sealing bushing 312 fixed in a circular aperture 314 in the top of the housing 302. As shown, the lower end of the busing 31-2 extends down into the housing 362 and forms a tight seal with the marginal edge of the aperture 314.

The lower end of the shaft 310 projects below the bushing 31-2 and connects nonrotatably with an actuator 3% which engages a follower 318 on the switch unit 390. The follower 318 coacts with a plunger 320 on the switch In addition, it has an improved spring acunit to operate the switch unit upon rotation of the shaft 310 to a critical switch operating position.

, The switch unit 3% is a precision, low travel switch in which the plunger 320 is functionally similar to the control plunger of the switching mechanism 92 shown in FIG. 2 and previously described.

An annular seal 222 fitted into a counter-bore 324 in the Y upper end of the bushing 312 in encircling relation to the I 30-8 rotatably relative to the shaft 319. This is accom piishe'd 'by means which provide for infinite adjustment of the arm to any desired position within a range of rotary adjustment extending through a complete revolution of the arm relative to the shaft and providing for projection of the arm in any desired direction from the shaft. Moreover, as will appear, the infinitely adjustable arm 3&8 is fixed in any position of adjustment in a manner which precludes the arm from working out of its position of adjustment on the shaft.

As shown in FIGS. 21 and 22, the shaft 310 extends upwardly through the shaft end of the arm 3'88, which is internally shaped to receive the shaft, as will presently appear. A rotary adjusting worm 326 extends transversely through the arm 30S and meshes with a worm gear 32-8 integrally formed on a portion of the shaft located within the shaft end of the arm, as shown. The worm 326 is held against axial movement relative to the'arm Silt? and is rotated to adjust the arm relative to the shaft by means of a slotted adjusting head 330* on the worm.

The portion of the shaft 31d intervening between the gear 328 and the seal 324- is shaped to fonnr a locking cone 332 which fits into a conically shaped portion 334 of the shaft receiving opening 336 in the arm. The upper end of the shaft 310 projects above the arm 398 and is threaded to receive a nut 33? which bears against the top 332 firmly into the arm opening portion 334 to produce a wedging action between the arm and shaft which assures holding of the arm rigidly in its adjusted position on the shaft.

This assures great accuracy and precision in the operation of the switch 298 for all positions of adjustment,

of the arm, while at the same time providing for adjustment of the arm to project the roller 306 in any desired direction from the housing 3&2. Two opposed clamping nuts 340-, 342 threaded onto the bushing 312 between the housing 392 and the arm 308 can be used in rigidly mounting the switch on support frame structure or the like (not shown).

A control switch 354} forming the modified embodiment of the invention illustrated'in FIGS. 23 to 25 comprises a housing or case 352 encasing a low travel switch unit 354- generally similar in its construction and operation to the switch mechanisms 92 and 92a shown in FlGS. V

2 and 16.

The switching unit -354- is operated by a plunger 356 a,

which projects outwardly from the housing 352 through a support boss or bushing 358. A support bracket 36%, secured firmly against a shoulder 362 on the bushing 358 by means of a nut 364 threaded onto the bushing in encircling relation to the plunger 356, carries switch control structure which actu ates the plunger 356 to operate the switch unit 354 in t 9 response to movement of an external machine element or the like 366 (shown in phantom in FIG. 24) into a critical control position relative to the switch 350.

Two sturdy support ears 368, 370 project upwardly from the bracket 360 to support trunnions 3-72, 374 on opposite ends of a control shaft designated generally by the number 376. A swingable control arm 378 is nonrotatably connected to the shaft 376 by splines 380 to cantilever away from the shaft, as shown, to support at the outer end of the arm a follower roller 382 adapted to engage an external element to which the switch is to respond.

The medial portion of the shaft 376 extends through an adjusting head or block 384 which journals a switch adjusting worm 336 in meshing relation to a worm gear 388 integrally formed on the shaft 376. The worm 386 is held against axial movement relative to the block 384 and is adjusted rotatably by insertion of a tool into a slot 390 in a head 392 on the worm to effect a progressive rotary adjustment of the head 334 relative to the arm 3-78.

The block 384 is firmly held in any position of rotary adjustment with respect to the arm 378 by tightening a nut 394 on the shaft 376 against one side of the head 384 to draw a conical element 396 on the shaft into a similarly shaped receiver 398 in the head.

An actuating arm 400 rigidly secured to the underside of the head 394, as shown in FIG. 24, extends into overlying relation to the projecting end of the plunger 356 to effect inward movement of the plunger and operation of the switch unit 354, upon rotation of the shaft 376 in a clockwise direction with respect to FIG. 24 to a predetermined control-position. A compression spring 4432 encircling the outer end of the plunger 356 acts on the projecting end of the arm 46% to urge the shaft 376 in a counterclockwise direction with reference to FIG. 24.

The switch 350 provides an unfailing retention of the control arm 378 and the actuating arm 4% in their preadjusted positions relative to each other, to assure precise operation of the switch upon movement of the coacting external element 366 into a critical control position. This certainty and reliability of the switch action is achieved in conjunction with the infinite adjustability of the switch to respond to the presence of external structure in different critical control positions relative to the switch.

It will be appreciated that the invention is not necessarily limited by the illustrations of the exemplary embodiments described, but includes variants within the scope of the invention as defined by the claims.

The invention is hereby claimed as follows 1. An electric switch mechanism comprising a housing, an operating lever extending through a wall of said housing, support means on said housing pivotally supporting said lever for swinging movement about a pivotal axis generally parallel to the portion of the housing wall located adjacent the lever and through which the lever extends, an electric switch device mounted within said housing, said electric switch device including a movable control member for the switch device and including resilient means biasing said control member in one direction, abutment means on said 'lever movable with the lever within said housing and defining an abutment disposed in proximity to said control member and facing in said one direction, said control member and said abutment having positions within said housing which are located in relation to each other and in relation to the position of said pivotal axis of said lever to cause said abutment to move in a direction generally parallel to said one direction upon swinging movement of said lever through small angles about said pivotal axis thereof, a cantilever spring extending across said abutment and having a base end anchored to said lever by means on the lever spaced an extended distance from said abutment and coacting with said spring to produce in the spring a residual bending stress urging the spring against said 1Q abutment, and said cantilever spring extending across said control member to move the latter against said resilient means in a direction opposite to said one direction to operate said switch device in response to predetermined swinging movement of said lever about said pivotal axis thereof. 7

2. An electric switch operating mechanism comprising a housing, a switch operating member extending through a wall of said housing and mounted for movement relative to said housing, an arm associated with said member to cause movement thereof relative to said housing, pivot means for said arm positioned adjacent one end thereof and located exterior of said housing for pivotal movement of said arm, roller means carried at the end of said arm opposite said pivot means, switch operating means disposed within said housingfor actuation by said member when the latter is actuated by said arm, and adjustment means associated with said pivot means to selectively re position the angular relationship of said arm to said housing and to said member, said adjustment means including locking means comprising tapered bushing means surrounding said pivot means and associated with said arm means, and'tightening means for said tapered bushing means, whereby said tapered bushing means may be tightened by said tightening means to lock said arm on said pivot means in a preselected angular relationship to said member and to said housing. a

3. A control switch adapted to respond to the position of external structure relative to the switch and comprising, in combination, a housing, a low travel switch unit incased within said housing, a rotary shaft extending into said housing, bearing means on said housing journalling said shaft for rotation, sealing means encircling said shaft and forming a seal between the latter and said housing, actuator means on the inner end of said shaft coacting with said switch unit to control the latter in response to rotation of the shaft to a predetermined critical control position, a control armrotatably mounted on the outer end of 'said shaft to project radially therefrom, an external object follower carried by the projecting end of said arm, a worm gear element non-rotatably secured to said shaft, an adjusting Worm journalled in said arm in meshing relation to said worm gear and fixed against axial movement relative to said arm, means for rotating said worm to effect adjustment of said arm about the axis of said shaft, a tapered element on said shaft fitting into a complementary opening in said arm, and threaded means coacting with said shaft to draw said tapered element firmly into engagement with said arm to tightly hold said arm against rotation relative to said shaft to retainsaid arm in the position relative to said shaft to which it is adjusted by rotation of said worm.

4. A'control switch adapted to respond to the position of external structure relative to the switch and comprising, in combination, a housing, a low travel switch unit incased within said housing, a rotary shaft extending into said housing, actuator means on the inner end of said shaft coacting with said switch unit to control theslatter in response to rotation of the shaft to a predetermined critical control position, ajcontrol arm swingably mounted on the outer end of said shaft to project therefrom, an external object follower carried by the projecting end of said arm, a worm gear element non-rotatably secured to said shaft, an adjusting worm journalled in said arm in meshing relation to said worm gear and fixed against axial movement relative to said arm, means for rotating said worm to effect angular adjustment of said arm relative to said shaft, a Wedge element on said shaft received in a complementary opening in said arm, and means coacting with said shaft to draw said wedge element firmly into engagement with said arm to tightly hold said arm in the position relative to said shaft to which it is adjusted by rotation of said worm.

5. -A loW travel control switch adapted to respond to movement of an external element into a critical control position relative to the switch and comprising, in combination, a housing, a switch unit mounted in said housing and including a control plunger projecting therefrom an external control shaft rotatably supported on said housing, a control arm non-rotatably fixed to said shaft and projecting radially therefrom, an external object follower carried by the projecting end of said control arm, an actuating arm supported on said shaft for rotation with respect thereto and projecting into coacting relation to said plunger, means for effecting an infinite adjustment of said actuating arm through an extended range of angular adjustment with respect to said shaft, said adjusting means including a worm gear on said shaft and a worm meshing with said gear and coacting with said actuating arm to rotate the latter with respect to said shaft; and means for retaining said actuating arm firmly in an adjusted position on said shaft and including a conical element, a conical receiver, and means for forcing said conical element into said receiver. 7

6. A low travel control switch adapted to respond to movement of an external element into a critical control position relative to the switch and comprising, in combination, a housing, a switch unit mounted in said housing and including a control plunger projecting therefrom, pivot means on said housing, a control arm supported on said pivot means and projecting radially therefrom, an external object follower carried by the projecting end of'said control arm, an actuator arm supported on said pivot means and projecting into coaoting relation to said plunger, means for efiecting an inifinite angular adjustment of said arms relative to each other through an extended angular range of adjustment, said adjusting means including a worm gear non-rotatably connected to one of said arms and a worm meshing with said gear and coacting with the other of said arms to rotate the latter with respect to said gear; and means for securing said arms in an adjusted angular position relative to each other and including a conical element non-rotatably connected to one of said arms, a conical receiver non-rotatably connected to the other arm, and means for forcing said conical element hard into said receiver.

7. A low'travel control switch, adapted to respond to movement of an external element into a critical control position relative to the switch and comprising, in combination, a housing, a switch unit incased in said housing, pivot means on said housing, an actuator armfswingably mounted on said pivot means, means interconnecting said actuator arm with said switch unit to effect operation thereof as an incident to swinging of said actuator arm into a critical control position, a swinging control arm, means interconnecting said control arm with said actuator arm for angular adjustment relative thereto, external object following means carried by said control arm for effecting a swinging movement thereof, means for effecting an infinite angular adjustment of said arms relative to each other through an extended angular range of adjustment, said adjusting means including a worm gear non-rotatably connected to one of said arms and a worm meshing with said gear and coacting with the other of said arms to rotate the latter adjustably with respect to said one arm; and means for securing said arms in adjusted angular positions relative to each other and including a conical element nonrotatably connected to one of said arms, a receiver for said conical element non-rotatably connected to the other arm, and means for forcing said conical element firmly into said receiver. 7 V

8. A low travel control switch adapted to respond to movement of an external element into a critical control position relative to the switch and comprising, in combination, a housing, a low travel switch unit mounted in said housing, pivot means on said housing, an actuating arm supported on said pivot means, means connecting said actuating arm to said switch unit to effect operation of the latter upon movement of said actuating am into a critical control position, a control arm pivotally connected adjnstably to said actuating arm and projecting therej from, an external object follower carried by said control: arm to effect swinging movement of the latter; and means for securing said arms in an adjusted angular position a relative to each other and including a conical element I non-rotatably connected to one of said arms, a receiverfor said conical element non-rotatahly connected to the 1 other arm,.and means for forcing said conical element hard into said receiver to hold said arms against rotation relative to each other. p p

9. A control switch adapted to respond to the position of external structure relative to the switch and comprising,

in combination, aho using, a low travel switch unit incased within said housing, a movable switch actuating ele ment supported on said housing for movement relative; thereto, means connecting said actuating element to said switch unit to effect operation of the latter as an incident a to movement of said actuating element into a predeter-w mined critical control position, a swingahle control arm pivotally interconnected adjustahly to said actuating elernent, an external object follower carried by said control anm to effect swinging movement thereof, means forecouring said control arm in various positions of an-gularadjustrnent relative to said actuating element; said securing means including a wedginlg element non-rotatably connected to said actuating element, a receiver for said wedging element non-rotatably connected to said arm, and means for releasably forcing said wedging element firmly into said receiver to fix said control arm against movement relative to said actuating element.

0. A control switch adapted to respond toythe posi to rotation of said shaft to a predetermined critical cont-rol position, a control anm swingably mounted on said shaft outside of said housing, a worm gear element nonrotatably secured to said shaft, an adjusting worm jour nailed in said arm in meshing relation to said worm gear 7 and fixed against axial movement relative tojsaid arm to effect angular adjustment :of said-arm relative to said shaft upon rotation of said worm, and means for releasably fixing said arm relative to said shaft independently of said worm to hold said anm solidly on said shaft in various positions of angular adjustment of said arm relative to said shaft.

11. A control switch adapted to respond to the position of external structure relative to the switch and comprising, in combination, a housing, a low travel switch unit incased within said housing, a notary shaft extending into said housing, actuator means connecting the innerfend of said shaft with said switch unit to control the latter in response to rotation of said shaft to a predetermined critical control position, a control arm defining an opening therethrough through which the outer end of said shaft extends to form for the arm a support about which the arm is swinga-ble for adjustment and from which the arm projects, a wedge element non-rotatably supported on said shaft, said arm including structure defining a generally smooth friction surface having an oblique relationship to the axis of said shaft and being shaped to confront and fit against said wedge element, tightening means threaded on said shaft to act through the shaft on the wedge element and coacting with said arm to react thereon to force said wedge element firmly against said friction surface to solidly yet releasably fix said arm in various positions of angular adjustment relative to said shaft, and worm means carried by said control arm for efiectin'g adjustment there of relative to said shaft uponloosening of said tightening means. 7 i i I 12. A switch operating mechanism adapted for use with I a low-travel control switch responsive to movement of an e external element into a critical control position; and comprising bracket means having means for mounting the same on a control switch, pivot means carried by said bracket means, an actuating arm supported on said pivot means, a control arm pivotally connected adjustably to said actuating arm and projecting therefrom, an external object follower carried 'by said control arm to effect swinging movement thereof; and means for securing said arms in an adjusted angular position relative to each other and including a conical element rnon-rotataoly connected to one of said arms, a receiver for said conical element nonrotatably connected to the other arm, and means for forcing said conical element hard into said receiver to hold the said arms against rotation relative to each other.

13. A switch operating mechanism as claimed in claim 12, wherein the conical element and receiver are concentric With said pivot means.

14. A switch operating mechanism as claimed in claim 13, wherein there is provided a worm gear cooperating 14 with said pivot means to effect relative adjustment between said arms upon release of engagement between said conical element and said receiver.

References Cited in the file of this patent UNITED STATES PATENTS 1,169,957 Henry Feb. 1, 1916 2,328,266 Dunbin Aug. 31, 1943 2,454,341 Repka Nov. 23, 1948 2,573,833 Christensen Nov. 6, 1951 2,677,023 Lee Apr. 27, 1954 2,786,916 Bordelon Mar. 26, 1957 2,794,889 Bachman et a1 June 4, 1957 2,795,959" Roescr June 18, 1957 2,806,114 Se Bastian Sept. 10, 1957 2,817,736 Se Bastian Dec. 24, 1957 2,821,610 Thomson et al Ian. 28, 1958 2,861,142 Millerwise Nov. 18, 1958 2,897,308 Fergus July 28, 1959 

2. AN ELECTRIC SWITCH OPERATING MECHANISM COMPRISING A HOUSING, A SWITCH OPERATING MEMBER EXTENDING THROUGH A WALL OF SAID HOUSING AND MOUNTED FOR MOVEMENT RELATIVE TO SAID HOUSING, AN ARM ASSOCIATED WITH SAID MEMBER TO CAUSE MOVEMENT THEREOF RELATIVE TO SAID HOUSING, PIVOT MEANS FOR SAID ARM POSITIONED ADJACENT ONE END THEREOF AND LOCATED EXTERIOR OF SAID HOUSING FOR PIVOTAL MOVEMENT OF SAID ARM, ROLLER MEANS CARRIED AT THE END OF SAID ARM OPPOSITE SAID PIVOT MEANS SWITCH OPERATING MEANS DISPOSED WITHIN SAID HOUSING FOR ACTUATION BY SAID MEMBER WHEN THE LATTER IS ACTUATED BY SAID ARM, AND ADJUSTMENT MEANS ASSOCIATED WITH SAID PIVOT MEANS TO SELECTIVELY REPOSITION THE ANGULAR RELATIONSHIP OF SAID ARM TO SAID HOUSING AND TO SAID MEMBER, SAID ADJUSTMENT MEANS INCLUDING LOCKING MEANS COMPRISING TAPERED BUSHING MEANS SURROUNDING SAID PIVOT MEANS AND ASSOCIATED WITH SAID ARM MEANS, AND TIGHTENING MEANS FOR SAID TAPERED BUSHING MEANS, WHEREBY SAID TAPERED BUSHING MEANS MAY BE TIGHTENED BY SAID LIGHTENING MEANS TO LOCK SAID ARM ON SAID PIVOT MEANS IN A PRESELECTED ANGULAR RELATIONSHIP TO SAID MEMBER AND TO SAID HOUSING. 